Thin Film (TF) heads--also called thin film inductive (TFI)--are a totally
different design from ferrite or MIG heads. They are so named because of how they are
manufactured. TF heads are made using a photolithographic
process similar to how processors are made. This is the same technique used to make
modern thin film platter media, which bears the same name; see
here for more details on this technology.
In this design, developed during the 1960s but not deployed until 1979, the iron core
of earlier heads, large, bulky and imprecise, is done away entirely. A substrate wafer is
coated with a very thin layer of alloy material in specific patterns. This produces a very
small, precise head whose characteristics can be carefully controlled, and allows the
bulky ferrite head design to be completely eliminated. Thin film heads are capable of
being used on much higher-density drives and with much smaller floating heights than the
older technologies. They were used in many PC hard disk drives in the late 1980s to mid
1990s, usually in the 100 to 1000 MB capacity range.
|
A pair of mated thin film head assemblies, greatly
magnified. The heads are
gray slivers with coils wrapped around them, embedded at the end of each
slider (large beige objects). One feed line (with green insulation) is visible. |
As hard disk areal densities increased, however, thin film heads soon reached their
design limits. They were eventually replaced by magnetoresistive
(MR) heads.
Next: (Anisotropic) Magnetoresistive (MR/AMR) Heads
